WO2009109667A1

WO2009109667A1 - Tool for the friction stir welding of two metal items with an angled joint having a pin and a wedge-shaped shoulder

Info

Publication number: WO2009109667A1
Application number: PCT/ES2008/000118
Authority: WO
Inventors: Leonardo MARTINEZ DÍEZ; Mari Luz Penalva Oscoz; Amaia OTAEGUI MARTÍN
Original assignee: Fundacion Fatronik
Priority date: 2008-03-03
Filing date: 2008-03-03
Publication date: 2009-09-11
Also published as: ES2449075T3; EP2266745A1; EP2266745B1

Abstract

The invention relates to a tool for the friction stir welding of two metal items with a joint angle of less than 180°, comprised of a shoulder (2) and a pin (3) which exits from said shoulder (2). Said shoulder (2) is wedge-shaped, with two walls (4) forming an angle equal to the angle of the joint of the two metal items and with an interference zone (5) at the meeting point of said walls (4). The interference zone (5) is configured so as to penetrate the metal items at the angle of their joint. The pin (3) exits from said interference zone (5). The shoulder (2) being thus configured, it may concentrate the pressure on the area on which the pin (3) operates.

Description

TOOL FOR THE FRICTION STIR WELDING OF TWO METAL ITEMS WITH AN ANGLED JOINT HAVING A PIN AND A WEDGE-SHAPED SHOULDER

D E S C R I P C I Ó N

FIELD OF THE INVENTION

The present invention belongs to the field of tools. More specifically, it refers to a tool for the welding of friction by two metal parts that will not form a flat joint, that is, whose joint angle is different from 180 °.

BACKGROUND OF THE INVENTION

Friction stir welding (FSW) has been invented, patented and developed for its industrial purpose by TWI

(The Welding Institute), in Cambridge, United Kingdom. US 5460317 discloses said friction beat welding process and constitutes the most descriptive text of this new welding technique.

Friction welding is a solid state joining technique, with no material input where the initial characteristics of the material remain. Using friction welding it is possible to weld different materials of great thickness obtaining excellent mechanical properties, and producing a very small distortion in the welded parts.

The basic concept is a non-consumable rotating tool with a profiled pin or rotor and a shoulder or cylinder of flat section, pin and shoulder in its English terminology, specifically designed. Said stud is inserted between the adjacent ends of the plates to be welded and crosses the entire joint line. There are two types of tools; The first and most basic is the rigid tool, where the pin does not have a movement relative to the shoulder. On the other hand there are tools where the pin has a relative movement with respect to the shoulder, this tool being called "FSW tool with retractable pin". The shoulder of the tool rotates in solidarity with the pin on most of the tools used, although there are also tools in which the shoulder does not rotate.

The functions performed by both the busty and the shoulder are as follows. On the one hand the shoulder carries out a pressure on the pieces to be welded. Said pressure, together with the rotation, causes a heating that leads to a plastic state to the metal that constitutes the metal parts, in the area surrounding the stud. Once the metals are in a plastic state, the brass beats said metals, and, by its turning process, drags the material around the tool, thereby causing welding as the tool advances and the material cools. In the beating process, the shoulder provides an additional service, which is to prevent the material from being expelled outside the contours of the tool, confining it to the initial geometry.

The design used today to make friction welding has a shoulder adapted to make flat joints, so it is not possible to insert it into pieces that have a certain angle between them.

Japanese patent JP 11320128 describes a configuration for welding two perpendicular walls in which the welding is carried out by means of a shoulder, which is supported by a wedge, and a stud, both rotating in solidarity. Said wedge has a through hole so that the stud can peek out and penetrate the pieces to be welded.

The tool described in this patent has the disadvantage that the shoulder has a flat section in each of the parts that rub with the piece This flat section is the one that the slab should perform, Due to its geometry, it would not be possible to forge the material to be welded, since the tool would be interlocked. Therefore, this geometry would not be suitable for proper forging of the material. On the other hand, this force is exerted on the shoulder of the tool with a rotating cylinder that is rotating in solidarity with the profiled rotor or pin, against the shoulder, with the consequent generation of unnecessary heat on the tool.

DESCRIPTION OF THE INVENTION

The invention relates to a tool for the welding of friction by two metal parts with a joint angle. The tool of the invention may be used to weld metal parts that form any angle, being preferably applied in those cases in which the angle of attachment is not flat. Typically the welding will be carried out of two metal parts at 90 ° degrees, although the invention can be used as already mentioned for any other angle. The tool comprises a shoulder and a stud. The busty comes out, emerges, or emerges from said shoulder.

In accordance with the invention, the shoulder is configured in the form of a wedge with two walls, the two walls of said wedge forming an angle substantially equal to the angle of union of the metal parts. In this way, the shoulder can be conveniently placed between the two metal parts in an adjusted manner, making the necessary pressure to weld both pieces and preventing the material during beating from being expelled outside the elements to be welded. During the realization of said welding, the shoulder will not rotate. In the union of said shoulder walls an interference zone is defined. The contact between the tool and the pieces to be joined will take place between the flat faces of the tool and the parts, maintaining the condition that the flat faces coincide with the plates to join between the flat faces adjacent to the interference zone of the tool and in the materials to be joined during welding or welding process. The interference zone has a first attack end and a second leak end. Welding will be carried out with a forward movement of the shoulder, the end of attack being the one that comes into contact with the two metal parts without them still being welded, the metal parts being welded once the leakage end is removed of metal parts. During welding, the interference zone will penetrate the metal parts until, as already mentioned, the contact of the wedge walls with the pieces to be joined. The stud comes out in said interference zone.

The interference zone may be configured such that all of it is a protuberance that emerges at the junction of the two wedge walls. Said protuberance allows the pressure to be concentrated in the angle of union of the two metal parts, as well as separating the interference zone from the wedge walls, so that when welding these walls do not penetrate the metal parts to be welded if not Only come into contact.

Said pin may exit the middle zone of the interference zone.

The interference zone may have a greater radius of curvature at the ends of said edge, that is, at the end of attack and the leakage end, than in the middle zone, that is, in the area where the stud comes out . The radius of curvature at the end of attack and leakage may be, for example, 2 millimeters, while the radius of curvature in the middle zone may be, for example, 0.5 millimeters. The evolution of the radius of curvature between both ends and the middle zone will be such that the radius of curvature progressively decreases. With this configuration, a series of advantages are achieved. In the first place, the greater radius of the attack and leakage ends helps the insertion of the tool in the event that geometric errors are observed in the pieces to be welded. Secondly, in the middle zone with a smaller radius of curvature, it will be favored for the tool to penetrate the material and produce a focused heating in said middle zone, aiding in welding. It is precisely for this reason that the brass comes out or arises in the middle zone, to beat the metal in the heated zone.

The interference zone may be shaped such that it is a protrusion protruding from the wedge walls. Said protuberance will occupy, for example, the first 0.8 millimeters of the wedge walls starting from the interference zone and will protrude, for example, 0.1 millimeters above the wedge walls. One of the purposes of the protuberance existing in the interference zone is that said interference zone can penetrate the metal parts to be welded without the shoulder walls penetrating said pieces. A possible way of making said protuberance is to make a recess in the walls of the wedge so that after the recess the protuberance described above appears. The wedge walls will rest on said metal parts, without penetrating them, so that the pressure communicated by the shaft will be applied only in those places where the pressure is required. The interference zone, therefore the tool, is designed not to penetrate more than this value, in the commented embodiment 0.1 millimeters, to carry out the plastic deformation of the material and to produce the consequent focused heating to aid in the realization of the welding. For this reason, the wedge walls will not penetrate the metal parts.

The shoulder may be symmetrical with respect to a plane perpendicular to the Ia interference zone and that cuts to said interference zone in the middle zone of said interference zone. In this way, the attack and leakage ends can be interchangeably interchangeably, being able, in the event that one of the ends wear out, continue welding at the other end, thus multiplying by two the useful life of the tool.

DESCRIPTION OF THE DRAWINGS

To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, a set of drawings is attached as an integral part of said description, in which, for illustrative and non-limiting purposes, Io has been represented. next:

Figure 1.- Shows a perspective view of the tool of the invention by welding two metal parts.

Figure 2.- Shows a perspective view of the tool. Figure 3.- Shows a detailed view of the interference zone.

Figure A - Shows a detailed view of the attack or leakage end.

Figure 5.- Shows a top view of the tool, in which three sections have been made.

Figures 5A-5C- Show the profile of the interference zone in the three sections made in Figure 5. Figure 6.- Shows a sectional view of the tool in the welding process.

Figure 6A.- Shows a view of the stud and the shoulder in a situation prior to welding, where the interference zone has not yet penetrated the metal parts to be welded. Figure 6B.- Shows a view of the pin and the shoulder in during the welding process, where the interference zone has still penetrated into The metal parts to be welded.

Figure 7.- Shows a detailed sectional view of the tool of the invention.

Figure 8.- Shows a perspective view of a tool designed to weld two metal parts with a joint angle greater than 180 °.

PREFERRED EMBODIMENT OF THE INVENTION

Next, with reference to the figures, a preferred embodiment of the machine tool for friction welding of two metal parts (1) with a joint angle of less than 180 ° which constitutes the object of this invention is described. .

Figure 1 shows the machine tool of the invention by welding two metal parts (1) with an angle of 90 °. Welding is being carried out from right to left, thus observing the leading edge (6) of the tool. As can be seen, the tool is composed of an axis (9) and a shoulder (2) comprising a wedge. Said wedge has two walls, which are cut at an angle equal to the angle formed by the two metal parts (1), in this case an angle of 90 °. The shaft (9) is responsible for transmitting the turning movement to the pin (3), in turn also transmitting the necessary pressure to the shoulder (2).

Figure 2 shows more clearly the tool of the invention.

In this figure it can be seen how the shoulder (2) is configured in the form of a wedge. Said wedge will have the opening of its two walls substantially equal to the opening of the two metal parts (1) to be welded, in this case 90 °. The two walls are in an interference zone (5), whereby the pin (3) comes out or emerges through its middle zone

(10) Said interference zone (5) has an attack end (6), which It will be the one that will enter the two pieces to be welded, and a leakage end (7), which will be the one that leaves the metal parts (1) once welded. In the described embodiment, the shoulder (2) is symmetrical with respect to a plane perpendicular to the interference zone (5) that passes through the middle zone (10) of said interference zone (5), so that the two extremes (6, 7) will be the same and both can perform the functions of attack or escape interchangeably. For this reason, in the event that the attack end (6) is worn so that it is not possible to weld at this end, the tool can be turned and continue welding at the other end, so that the tool life is doubled.

Figure 3 shows a detail of the interference zone (5), in particular from the hole through which the pin (3), to one of the two ends (6, 7) of the interference zone (5), either the attack end (6) or the leakage end (7), which as already mentioned are equivalent. In said figure it can be seen how the radius of curvature is greater at the end of attack (6) or leakage, for example with a value of 2 millimeters of radius, while said radius of the interference zone (5) is decreasing progressively to the area near the hole through which the pin (3), that is, the middle zone (10) of the interference zone

(5), where it reaches its smallest radius of curvature, for example with a value of 0.5 millimeters. These two values are two orientative and non-limiting values, used in this embodiment, but the following values would be equally valid: 1.75 millimeters - 0.45 millimeters, or 1.65 millimeters - 0.40 millimeters, that is, any pair of values in which the radius of curvature of the attack end (6) and leakage is greater than the radius of curvature of the middle zone (10) of the interference zone (5).

The aim pursued with this difference in curvatures is that the radius of curvature at the end of attack (6) sufficient to be able to progressively penetrate the piece and compensate or mitigate possible errors geometric of the metal parts (1). As the radius of curvature decreases, the interference zone (5) is able to penetrate more into the welding line. The penetration will be maximum in that zone in which the radius of curvature of the interference zone (5) is minimal, that is, in the middle zone (10) of said interference zone (5), that is, where it is located the busty (3). It will therefore be in this area, the middle zone (10), in which the effective shoulder pressure (2) will be maximum, therefore, where the heat produced by the friction will be concentrated, leaving the rest of the areas of the stud (3 ) free of this effect. Thus, the operation of the machine is more efficient since the heat is concentrated only in that area in which it is to be produced. This place is where the pin (3) is located, so that the work done by it will be favored by this concentrated heat.

Figure 4 shows an optimization of the wedge design. Said optimization consists in that the interference zone (5) comprises a protuberance that protrudes 0.1 millimeters in the wedge walls. This protuberance must be such that, when the interference zone (5) penetrates the welding line, the shoulder walls (2) do not prevent said penetration. If it is estimated that the penetration of the interference zone (5) is of a value close to but less than 0.1 millimeter, the proposed value of 0.1 millimeters achieves the intended purpose. With this protuberance the walls of the shoulder (2) will not affect or prevent the penetration of the tool, and in the same way will allow to guide said tool since they will be close or in contact with the metal parts (1) to be welded. In the case shown in the figures, said protuberance has been made by means of a recess (8) in the wedge walls, this recess (8) being 0.1 millimeters.

In order to soften the possible living edges existing in the shoulder (2), for example in areas such as the encounter of the recess (8) of the Ia wall (4) of the wedge and the interference zone (5), said edges are provided to be rounded with a radius of less than 0.2 millimeters. With the roundness that these arcs create, it is possible to soften the contours and minimize the risk of breakage of the tool.

In the process of manufacturing the shoulder (2), the progressive radius is first made from the ends of the piece to the center of the tool. Then the recesses are made in the walls of the wedge, which have a depth of 0.1 millimeters, but leaving in the interference zone (5), 0.8 millimeters as a protuberance. Finally, rounding of the living edges is performed.

Complementing Figures 3 and 4, Figures 5, 5A, 5B and 5C show an evolution of the interference zone (5) in three different points of the shoulder (2). In these figures a smaller radius appears in all of them, which would correspond to the radius in the mid-plane of the shoulder (2), that is, at the point where the pin (3) comes out or emerges, this plane represented in the figure 5C. According to the cutting plane moves away from this middle plane, figures 5A and 5B, a larger radius appears that is maximized at the two ends (6, 7) of the tool.

Figure 6 shows a sectional view of the tool in which the operation of the pin (3) can be observed. As can be seen, the shaft (9) simultaneously provides a rotational movement that allows the pin (3) to penetrate the metal parts (1) to be welded and advanced along

The welding line, and additionally transmits enough pressure to the shoulder (2) to forge the beaten material by the brass of the metal parts (1) leading them to a state of plasticity necessary to carry out the welding. The detail view of Figure 6A allows to observe how the pin (3) has penetrated the two metal parts (1), but nevertheless welding is not yet performed, since the interference zone (5) does not It has penetrated the metal parts (1) to be welded. In Figure 6B, it can be seen as the interference zone (5) and the protuberance that this shape has penetrated into the metal parts (1) to be welded. This penetration causes the heating of the joint angle or welding line of the two metal parts (1) to be welded, without which the welding (or the realization of the welding) could not occur.

Figure 7 shows a detail of the tool described in which it is possible to observe the way in which the shaft (9) simultaneously transmits a rotating movement to the pin (3) and a pressure to the shoulder (2). The shaft (9) transmits the pressure by means of a washer joined in solidarity with the shaft that bumps against a bush connected to the structure of the shoulder by means of bearings. The pressure of the shaft (9) communicated to the bushing through the washer is communicated to the shoulder (2) and is applied in the interference zone (5). In the same way, the shaft (9) additionally rotates, and that turning movement is communicated to the pin (3) through a connecting element located at the end of the shaft (9). These two movements of the shaft, the pressure and the rotation allow welding to the described tool.

Up to this point, a shoulder (2) with an angle less than 180 °, specifically 90 °, has been commented. Any other angle less than 180 ° would look similar to that described in the previous figures. Figure 8 shows the appearance of a shoulder (2) designed for an angle greater than 180 °. Said shoulder (2) can be applied when it is not possible to weld inside the metal parts (1) or when it becomes necessary to weld both inside and outside the pieces. As can be seen, the characteristics of the shoulder (2) remain, and it can be seen that the shoulder (2) forms the same angle as the metal parts to be welded (1), not shown, as well as an interference zone (5) able to penetrate the joint angle during welding. In the event that it is desired to weld two metal parts (1) that form a plane, the invention would also be applicable. In this circumstance the heat that was previously obtained by the rotation of the shoulder (2) would now be produced by the penetration of the interference zone (5) in the welding line.

In view of this description and set of figures, the person skilled in the art may understand that the invention has been described according to a preferred embodiment thereof, but that multiple variations can be introduced in said preferred embodiment, without leaving the object of the invention as claimed.

Claims

1.- Tool for the welding of friction by two metal parts (1) with an angle of union, which includes a shoulder (2) and a pin (3) that comes out of said shoulder (2), characterized in that the shoulder

(2) is wedge-shaped with two walls, the two walls of said wedge forming an angle substantially equal to the angle of union of the metal parts (1), said shoulder (2) comprising an interference zone (5) in The union of said two walls, with a first end of attack (6) and a second end of leakage (7), said interference zone (5) configured for, during welding, penetrating the metal parts (1) to the contact of the wedge walls with the pieces to be joined (1), the pin (3) coming out in said interference zone (5).

2.- Tool for friction whipping welding according to

The claim 1, characterized in that the interference zone (5) comprises a protuberance in the union of the two walls of the wedge.

3. Tool for welding friction beating according to any of claims 1-2, characterized in that the pin (3) comes out in a middle area (10) of the interference zone (5).

4. Tool for friction whipping welding according to claim 3, characterized in that the interference zone (5) has a greater radius of curvature at the attack end (6) and the leakage end

(7) that in the middle zone (10) of the interference zone (5).

5. Tool for friction whipping welding according to claim 4, characterized in that the radius of curvature of the interference zone (5) decreases progressively from the attack end (6) and the leakage end (7) to The middle zone (10) of said edge.

6. Tool for friction whipping welding according to any of claims 1-5, characterized in that the wedge walls have a recess (8) outside the interference zone (5) on the surface in contact with the two metal parts (1) during welding.

7. Tool for friction whipping welding according to any of claims 1-6, characterized in that the shoulder (2) is symmetrical with respect to a plane perpendicular to the interference zone (5) and cuts to said area of interference (5) in the middle zone (10) of said interference zone (5).

8. Tool for friction whipping welding according to any of claims 1-7, characterized in that the radius of curvature of the interference zone (5) at the first end of attack (6) and at the second end of leakage (7) is less than 2 millimeters.

9. Tool for friction whipping welding according to any of claims 1-8, characterized in that the radius of curvature of the interference zone (5) in the middle zone (10) is less than 0.5 millimeters.

10. Tool for welding friction beating according to claim 6, characterized in that the recess (8) of the wedge walls is less than 0.1 millimeters.

11. Tool for friction whipping welding according to claim 2, characterized in that the protuberance occupies the first 0.8 millimeters of the surfaces of the wedge from the interference zone (5).

12.- Machine tool comprising a tool according to claims 1-10.